In result of a lew years' investigations or silting of small water reservoirs located in South Poland, intensity ofthe silting process as well as the granulometrie and chemical composition ofbottorn sediments were evaluated. The content of heavy metals i.e. copper, lead and cadmium was determined in samples collected in various parts or five small water reservoirs. The content of heavy metals was appraised according to the regulation of the Minister of Environment, according to the criteria or Polish Geological Institute, of Inspection lor Environmental Protection, of Institute of Soil Science and Plant Cultivation, and according to the Muller's method. The obtained results or determination of the examined heavy metals concentrations were compared with the values or reservoir and river sediment concentrations determined by other authors in Europe. Appraisal or sill quality, respectively to the adopted criteria, showed only an insignificant degree of pollution. Concentrations ofmicroclemcnts do not exceed the toxic concentrations for soils and environment bul may have a harmful influence on living organisms. Recording of changes or heavy metal pollution during many years' operation or small water reservoirs, considering changes occurring in the basins, requires continuation of investigations. It will enable to record changes or pollution during a longer period or operation or reservoirs, also against the background 01· changes occurring in river basins.

The aim of the study was fractionation of Zn, Cu, Ni, Pb in the bottom sediments of two small reservoirs: at Krempna on the Wisłoka River and at Zcslwicc on the Dlubnia River. The partitioning of metals for various fractions was performed with the use of Tessier's sequential chemical extraction method. All together five metal fractions were distinguished: exchangeable metals (fraction I), metals bound to carbonates (fraction II), metals bound to hydrate Fe-Mn oxides (fraction III), metals bound to organic matter (fraction IV), and metals bound to minerals (fraction V). The largest quantities of metals were bound with fraction V, the smallest occurred in the forms most easily available for living organisms, in faction I. Proportions ofZn, Ni and Pb in the exchangeable fraction were about 1%. The amounts of metals bound with fraction II were also relatively low, except lor Zn in bottom sediment at the Zeslawice Reservoir. In this bottom sediment the share of Zn bound to carbonates was 33%. Medium metal quantities were associated with hydrate Fe-Mn oxides (fraction III) and with organic matter (fraction IV). Relatively high proportion ofmetals in fraction V and trace amounts ofmetals in fraction I as well as alkaline and neutral reaction of the sediments may prove a potentially low hazard of the metal release in the case of chemical changes in the reservoirs.